Pressure indicator



June 9, 1936. J. H. WOODBERRY PRES SURE INDICATOR Filed Aug. 16, 1953 3Sheets-Sheet l' INVENTOR. Jul-m H- Wm: 1:11: Erry BY Wm M ATTORNEY June9, 1936. I Y J WOQDBERRY I 7 2,043,277

PRESSURE INDICATOR Filed Aug. 16, 1933 I5 SheetsSheet 2 invents? rlmhn H.Wu and]: Err'y 2v ///4/ ZWZ Attmvnaayv PRESSURE INDICATOR WMM M n mPatented June 9, 1936 UNITED STATES PRESSURE INDICATOR John Woodberry,United States Army, FortBliss, Tex.

Application August 16,

9 Claims.

1933, Serial No. 685,473

(Granted under the act of March 3, 1883, as

amended April -30,

.The invention described herein may be manufactured and used by or forthe-Government for governmental purposes, withoutjthe payment to me ofany royalty thereon.

The subject of this invention isapressure i-ndicator intended primarilyfor use with pneumatic tires.

The principal damagesto pneumatic tires on vehicles occur throughoperating .at pressures above or below those for which the tires aredesigned. Low pressure maybe due to inattentiveness or to punctures,leaks; etc. High pressures may arise through error in filling or throughroad heat resulting frequently in blowouts or serious accidents. In mostinstances these, occurrences would be avoided if the operators'attention were attractedto the tires when improper airpressureconditions arise. In the invention described herein there have beendevised means for-warning'the operators of vehicles wheninjurious ordangerous conditions exist.

To the foregoing .ends .mea-ns have. beenprovided, normallyinoperative-but operating upon either high pressure or low pressure toindicate-an abnormal condition of pressure. Such means consistsessentially of a switch-or contact, operating automaticallyto indicatethrough mechanical or electrical means-theabnormal conditions ofpressure.

Practical embodiments of :the invention are illustrated in theaccompanying drawings, where- Fig. 1 is a fragmentary view of a wheel.with the pressure indicator operatingv means shown in elevation in placethereon and in operative position. Fig. .2 isan enlargedlongitudinalsectional view of the indicator.

Fig. 3 is a detail perspectiveview, parts broken away showing the partspartially disassembled.

Figs. 4,.5 and 6 are fragmentary sectional views showing positionsassumed during operation under low pressure.

Figs. 7 and .8 are fragmentaryviews showing positions assumed duringoperationunder high pressure.

Fig. 9 is a longitudinalsectional viewof a modified form designedtoindicate. low pressureonly.

Fig. 10 is .a longitudinalsectional-view .of another modification ,ofthe. low pressure indicato and Fig.11 is a similar. view of another form.of high and low pressure indicator. I

Referringto, the drawings by numerals of. reference:

.A wheelis indicatedat l,.provided with-ariml 1928; 370" O. GC757) uponwhich is seated .a-tire rim,.3, for-holding .a tire consisting of acasing 4 and. a tube 5. As a protection to the tubethere isusuallysupplied-a flap 6 between the tube and the tire rim.

A housing 1 preferably tubular and .exteriorly l I, the outerprotrudingend of .WhlCh is provided with an angularly disposed arm; I2 which33.0135 as a contactmember to closean-electricalcircuitor operate amechanical indicatingmeans. ;Inthe Wall of the housing I is formed aslot l3 into which projectstheend of a pin 14;:suitably secured to theshaft ll and extending radially therefrom. The slot I3 is of greaterdepth than the diameter of the pin to allow-slight movement of the shaftlongitudinally of the housing and the ends of the slot form stops tolimit axial rotation of the shaft.

Surrounding that portion of the :shaft within the housing I is a torsionspring l5, one end of which is anchoredin the housing :,and the otherend anchored to the shaft I l which-spring tends to rotate the shaftabout its axis-butis restrained therefrom bythe elements immediately vto:be described.

.A pin.- [6 is carried by the shaft. l I- which normally rests in one ofapair of grooveslll'| stamped in a washer l8 'andextendingdiametricallythereof. The washer I8 is slidableonrthe shaft II and normally rests :onthe outer-end of the housing with the endsuof the grooves". in positionto receive thetongues l9 providedqon the end of said'housing. Slidable.on the shaft H and resting on the washer i8 is a washer and confinedbetween this washer anda screw;cap 2| which is threaded on the housing!is anompression spring22 which surrounds the ,shaftand which may becompressed 'byadjustment of the screw cap 2| to predetermine the, forceqnecessary vto;perrnitescape of thepin ifi -fromgthegroove I1 under thetension of ithetorsion spring [-5 when pressure is low or topermituwasher-lfi. toride over the tongues I9 under thetensionrofthetorsion spring l5 when the pressure is'ihigh. The. screw cap. 2 I maybe held in ladiustedposition 'by suitable means.hereinqshowngas :a setscrew 23.

Figure .11 isa variation -of.=.-Eigur.ei2. .Inithis figure ahousinglb isattacheddo theztire. rimin the manner shown in Figure 2. The pressurehead I01) and shaft I lb operate with respect to the housing lb and witheach other similar to corresponding parts in Figure 2. Rotation of theshaft however is limited by shoulders 28 presented by a substantiallysemi-cylindrical projection at the end of the housing lb instead of aslot as at I3, Figure 3. One end of the shaft is serrated and threadedto permit adjustments of the arm I2b. From the foregoing it will beunderstood that the arm I2b performs both the functions of the arm l2 inthe preferred form and of the pin I4, acting as a contact member andalso as a stop to limit axial rotation of the shaft by engaging theshoulders 28.

The torsion spring I5?) is anchored and operated similar to spring I5 inFigure 2, and tends to rotate the shaft I lb about its axis.

In this variation a serrated clutch plate I81) which engages a serratedclutch surface in the head of the housing is employed to restrainrotation of the shaft in lieu of the grooved plate washer I8. Thisclutch plate I82) is slidably and rotatably mounted on the shaft I lb. Across pin I6b passing through the shaft, resting in a groove III) in theclutch plate prevents rotation of the shaft with respect to the clutchplate, until the tire pressure exceeds a desirable limit, when, actingcounter to the compressed spring 22b, the pin lBb is raised out of thegroove I'lb allowing the shaft to be rotated by the torsion spring I5b.

The clutch plate I8b which is locked to the shaft by means of cross pinI61), also prevents rotation of the shaft until the tire pressure dropsbelow safe limits, at which time the shaft rotates under the influenceof the torsion spring I5b.

Means for adjusting the compression spring to correspond to a desiredupper limit of the pressure are afforded through a nut 212) which isthreaded to the shaft Ilb. Adjusting means for the torsion spring l5bare obtained through shifting the position of the arm I2b on the end ofthe shaft I lb so as to provide desired torsional effect.

The modified form shown in Fig. 9 operates on the same principle as theone just described but is designed for slow moving vehicles where roadheat and consequent high pressure is not a factor and indicates lowpressure only. In this instance the housing la. is formed with a. head-l8a in which the diametrically disposed grooves I'Ia are formed for thereception of the pin IS. The cap 2 la may have a sliding fit on thehousing 'la and the adjustment thereof made through a nut 24 engagingthe cap and threaded on the shaft llc.

A further embodiment of this invention in a low pressure indicator isshown in Fig. 10. This adaptation involves the use of the valve stem asa pressure element. It has the advantage of eliminating an extra hole inthe wheel and tire rims, and is particularly adaptable for use withWheels which have separate tire rims.

A housing 1c, preferably tubular and exteriorly threaded, passes throughand is clamped in the wheel rim 20 by means of a head I0 and a nut 80.When the tire rim 3c and tire are in place the valve stem Illc protrudesthrough the housing. The outer end of the housing is formed withshoulders 28 in a manner to limit the movement of the arm I20 of theshaft llc.

Adjustably positioned on the valve stem is an annular fluted orroughened clutch member l8c.

Within the housing 1c and surrounding the valvestem, slidable androtatable withrespect thereto is a hollow shaft He provided on one endwith an angularly disposed arm I20 which acts as a contact member tooperate a warning signal, and on the other end with a fluted orroughened clutch plate I40 which engages in 5 pressure contact withclutch member threaded on the valve stem. The shaft is restrained fromoutward axial movement by an annular shoulder 210 which rests againstthe inner end of the housing 1c.

Surrounding shaft I I0 within the housing la is a torsion spring I50,one end being anchored to the shaft He, the other end being anchored tothe housing 10, which spring tends to rotate the shaft about the valvestem, but is restrained therefrom by clutch contact between plate I40and clutch member I8c.

The operation of the device in its preferred form is as follows.

The desired adjustment having been made, when pressure within the tube 5falls below normal to a critical extent pressure on the head I0 isrelieved sufficiently to permit the force exerted by the torsion springI5 to exceed the force tending to hold the pin IS in a groove I! so thatthe pin will be displaced from the groove and the shaft rotated untilthe pin I l arrives at an end of the slot I3. In this rotated positionof the shaft the arm I2 is brought against an electrical switch handle25 of switch 26, which is attached to a non-rotating part of thevehicle, to effect the operation of a horn, bell, buzzer, light or othersignal, or the arm I2 may mechanically operate the clapper of a bell oneach revolution of the wheel.

When pressure within the tube 5 becomes excessive the head It is actedupon to slightly compress the spring 22 when the force exerted by thetorsion spring I5 will overcome the force tending to hold the Washer l8seated on the'end 40 of the housing I with the tongues I8 engaged in thegrooves I1 and will force the washer to ride over the tongues and theshaft to rotate with the result heretofore described.

The device, after operation thereof, is restored 45 to normal positionwith the arm I2 lying in the plane of the wheel by grasping the arm I2and rotating the shaft back to normal, where it will remain if pressurewithin the tube 5 has been restored to normal.

In the modified form shown in Fig. 10 the operation is as follows:

Pressure from within the tube forces the valve stem head towards thetire rim with a pressure varying with the air pressure. By suitableadjustment of clutch member I80, which is attached to the valve stemthis pressure may be transferred from the wheel rim to the clutch plateof the plunger Ilc. This engagement and pressure are used to preventrotation of the plunger I I0 while the tire pressure is suflicient toprevent injury. If the tire pressure decreases to a critical pointhowever, the clutch releases, permitting the plunger to rotate andoperate the alarm means.

In the form shown in Fig. 9, when pressure within the tire drops belownormal the force tending to retain the pin IS in the groove I la isreduced and when such reduction becomes sufficient the force of thetorsion spring is sufficient 70 to cam the pin I 6 out of the groove androtate the member He.

The operation of the form shown in Fig. 11 is as followsr-When pressurein the tire becomes excessive, the head IIIb' is forced further into 76Cir the housing 1b thereby moving the rod D to free the pin lBb from thegroove l'lb allowing the torsion spring lib to rotate the rod lib andwith it the arm I21). When pressure drops below normal the pressure onthe head I!) is no longer sufficient to overcome the force of thetorsion spring lb tending to turn the rod lib and the rod willconsequently be turned, the clutch member i817 riding over thecooperating surface on the housing lb.

I claim:-

1. A tire pressure indicator embodying a housing, a shaft within thehousing adapted to be acted on by the tire, means for holding the shaftin normal position during predetermined pressure ranges within the tire,a torsion spring for rotating the shaft when the pressure within thetire falls without such predetermined pressure ranges, and a membercarried by the shaft and positioned, when the shaft is thus rotated, totrip an indicating means.

2. A tire pressure indicator embodying a housing having an open end,means for securing the housing in fixed relation to a wheel rim with theopen end directed toward a pneumatic tire carried by said rim, a shaftwithin the housing, a pressure element rotatable relatively to the shaftand carried thereby in position to contact that portion of the tirebridging the open end of the housing, means within the housing forholding the shaft in normal position during predetermined pressureranges within the tire, and means for rotating the shaft when thepressure within the tire falls without such predetermined pressureranges.

3. A tire pressure indicator embodying a housing having an open end,means for securing the housing in fixed relation to a wheel rim with theopen end directed toward a pneumatic tire carried by said rim, a shaftwithin the housing, a pressure element rotatable relatively to the shaftand carried thereby in position to contact that portion of the tirebridging the open end of the housing, means within the housing forholding the shaft in normal position during predetermined pressureranges within the tire, and a resilient element for rotating the shaftwhen the pressure within the tire falls without such predeterminedpressure ranges.

4. A tire pressure indicator embodying a housing having an open end,means for securing the housing in fixed relation to a wheel rim with theopen end directed toward a pneumatic tire carried by said rim, a shaftwithin the housing, a pressure element rotatable relatively to the shaftand carried thereby in position to contact that portion of the tirebridging the open end of the housing, means within the housing forholding the shaft in normal position during predetermined pressureranges within the tire, means for rotating the shaft when the pressurewithin the tire falls without such predetermined pressure ranges, and amember carried by the shaft and positioned, when the shaft is rotated,to

' trip an indicating means.

5. A tire pressure indicator embodying a housing having an open end,means for securing the housing in fixed relation to a wheel rim with theopen end directed toward a pneumatic tire carried by said rim, a shaftwithin the housing, a pressure element rotatable relatively to the shaftand carried thereby in position to contact that portion of the tirebridging the open end of the housing, means within the housing forholding the shaft in normal position during predetermined pressureranges within the tire, a resilient element for rotating the shaft whenpressure within the tire falls without such predetermined pressureranges, and a member carried by the shaft and positioned, when the shaftis thus rotated, to trip an indicating means.

6. A tire pressure indicator embodying a housing having an open end,means for securing the housing in fixed relation to a wheel rim with theopen end directed toward a pneumatic tire carried by said rim, a shaftwithin the housing adapted to be contacted by that portion of the tirebridging the open end of the housing, a torsion element exerting a forceto rotate the shaft, pressure means adjustable to overcome the torsionforce during predetermined pressure ranges within the tire, and a membercarried by the shaft and positioned when the shaft is rotated by thetorsion element to trip an indicating means.

7. A tire pressure indicator embodying a. housing having an open end,means for securing the housing in fixed relation to a wheel rim with theopen end directed toward a pneumatic tire carried by said rim, a shaftwithin the housing adapted to be contacted by that portion of the tirebridging the open end of the housing, a torsion element exerting a forceto rotate the shaft,

and pressure means adjustable to overcome the torsion force duringpredetermined pressure ranges within the tire.

8. A tire pressure indicator embodying a housing having an open end,means for securing the housing in fixed relation to a wheel rim with theopen end directed toward a pneumatic tire carried by said rim, a shaftwithin the housing adapted to be contacted by that portion of the tirebridging the open end of the housing, a torsion element exerting a forceto rotate the shaft, pressure means adjustable to overcome the torsionforce during predetermined pressure ranges within the tire, and anelement secured to the shaft and cooperating with elements on thehousing to limit rotation of the shaft.

9. A tire pressure indicator embodying a housing having an open end,means for securing the housing in fixed relation to a wheel rim with theopen end directed toward a pneumatic tire carried by the rim, a shaftwithin the housing adapted to be contacted by that portion of the tirebridging the open end of the housing, a torsion element exerting forceto rotate the shaft, pressure means adjustable to overcome the torsionforce during predetermined pressure ranges within the tire, an elementsecured to the shaft and cooperating with elements on the housing tolimit rotation of the shaft, and a member carried by the shaft andpositioned when the shaft is rotated by the torsion element to trip anindicating means.

JOHN H. WOODBERRY.

